The motion of a droplet subjected to linear shear flow including the presence of a plane wall

1995 ◽  
Vol 302 ◽  
pp. 45-63 ◽  
Author(s):  
W. S. J. Uijttewaal ◽  
E. J. Nijhof
Keyword(s):  
Shear Flow ◽  
Flow Field ◽  
Theoretical Models ◽  
Boundary Integral ◽  
Plane Wall ◽  
Time Dependent ◽  
Fluid Inertia ◽  
Linear Shear ◽  
Material Element ◽  
Migration Velocities

A fluid droplet subjected to shear flow deforms and rotates in the flow. In the presence of a wall the droplet migrates with respect to a material element in the undisturbed flow field. Neglecting fluid inertia, the Stakes problem for the droplet is solved using a boundary integral technique. It is shown how the time-dependent deformation, orientation, circulation and droplet viscosity. The migration velocities are calculated in the directions parallel and perpendicular to the wall, and compared with theoretical models and expeeriments. The results reveal some of the shortcomings of existiong models although not all diserepancies between our calculations and known experiments could be clarified.

The inertial lift on a rigid sphere translating in a linear shear flow field

1994 ◽  
Vol 20 (2) ◽  
pp. 339-353 ◽  
Author(s):  
P. Cherukat ◽  
J.B. McLaughlin ◽  
A.L. Graham
Keyword(s):  
Shear Flow ◽  
Flow Field ◽  
Rigid Sphere ◽  
Linear Shear

The inertial lift on a rigid sphere in a linear shear flow field near a flat wall

1994 ◽  
Vol 263 ◽  
pp. 1-18 ◽  
Author(s):  
Pradeep Cherukat ◽  
John B. Mclaughlin
Keyword(s):  
Shear Flow ◽  
Flow Field ◽  
Lift Force ◽  
Point Force ◽  
Rigid Sphere ◽  
Flat Wall ◽  
Linear Shear ◽  
Inner Region ◽  
Infinite Wall

An expression which predicts the inertial lift, to lowest order, on a rigid sphere translating in a linear shear flow field near a flat infinite wall has been derived. This expression may be used when the wall lies within the inner region of the sphere's disturbance flow. It is valid even when the gap is small compared to the radius of the sphere. When the sphere is far from the wall, the lift force predicted by the present analysis converges to the value predicted by earlier analyses which consider the sphere as a point force or a force doublet singularity. The effect of rotation of the sphere on the lift has also been analysed.

A sphere in a uniformly rotating or shearing flow

2008 ◽  
Vol 600 ◽  
pp. 201-233 ◽  
Author(s):  
J. J. BLUEMINK ◽  
D. LOHSE ◽  
A. PROSPERETTI ◽  
L. VAN WIJNGAARDEN
Keyword(s):  
Shear Flow ◽  
Toroidal Vortex ◽  
Fluid Inertia ◽  
Incident Flow ◽  
Near Wake ◽  
Particle Spin ◽  
Shear Component ◽  
Linear Shear ◽  
Flow Components ◽  
Surrounding Fluid

It is known that, in a linear shear flow, fluid inertia causes a particle to spin more slowly than the surrounding fluid. The present experiments performed with a sphere with fixed centre, but free to rotate in a fluid undergoing solid-body rotation around a horizontal axis indicate that the spin rate of the sphere can be larger than that of the flow when the sphere is sufficiently far from the axis. Numerical simulations at Reynolds number 5≤Re≤200 confirm this observation. To gain a better understanding of the phenomenon, the rotating flow is decomposed into two shear flows along orthogonal directions. It is found numerically that the cross-stream shear has a much stronger effect on the particle spin rate than the streamwise shear. The region of low stress at the back of the sphere is affected by the shear component of the incident flow. While for the streamwise case the shift is minor, it is significant for cross-stream shear. The results are interpreted on the basis of the effect of the shear flow components on the quasi-toroidal vortex attached in the sphere's near wake. The contributions of streamwise and cross-stream shear to the particle spin can be linearly superposed forRe=20 and 50.

Experimental observation of viscoelastic fluid–structure interactions

2017 ◽  
Vol 813 ◽  
Author(s):  
Anita A. Dey ◽  
Yahya Modarres-Sadeghi ◽  
Jonathan P. Rothstein
Keyword(s):  
Flow Instability ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Flexible Structure ◽  
Fluid Inertia ◽  
Fluid Structure Interactions ◽  
Periodic Oscillations ◽  
Fluid Structure ◽  
Dependent Growth ◽  
First Time

It is well known that when a flexible or flexibly mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices. Here, we show for the first time that fluid–structure interactions can also be observed when the fluid is viscoelastic. For viscoelastic fluids, a flexible structure can become unstable in the absence of fluid inertia, at infinitesimal Reynolds numbers, due to the onset of a purely elastic flow instability. Nonlinear periodic oscillations of the flexible structure are observed and found to be coupled to the time-dependent growth and decay of viscoelastic stresses in the wake of the structure.

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